1. Field of the Invention
This invention relates to an antibody or a peptide capable of specifically binding to human VEGF receptor Flt-1 which is useful for the diagnosis or treatment of diseases in which their morbid states progress by abnormal angiogenesis, such as proliferation or metastasis of solid tumors, arthritis in rheumatoid arthritis, diabetic retinopathy, retinopathy of prematurity and psoriasis; a hybridoma capable of producing the antibody; a method for immunologically detecting human VEGF receptor Flt-1 using the antibody or the peptide; and a diagnostic method and a therapeutic method for diseases, such as solid tumor, rheumatoid arthritis, diabetic retinopathy, retinopathy of prematurity, psoriasis and the like, using the antibody or the peptide.
2. Brief Description of the Background Art
Angiogenesis plays an important role in the individual development and construction of tissues in vertebrates, is directly involved in the formation of the corpus luteum during the sexual cycle, transient proliferation of the uterine endometrium and formation of the placenta in mature individuals (females). With regard to pathological states, angiogenesis is involved in the proliferation or metastasis of solid tumors and formation or acceleration of morbidity in diabetic retinopathy and rheumatoid arthritis [J. Biol. Chem., 267: 10931 (1992)]. Angiogenesis occurs by the secretion of an angiogenesis factor and involves the process of a tube formation and producing a new blood vessel. During this process, the basement membrane and interstitum are destroyed by a protease secreted from endothelial cells of an existing blood vessel around the secreted angiogenesis factor, followed by subsequent migration and proliferation of vascular endothelial cells [J. Biol. Chem., 267: 10931 (1992)]. Factors which induce angiogenesis include vascular permeability factor (hereinafter “VPF”) and vascular endothelial growth factor (hereinafter “VEGF”) (hereinafter “VPF/VEGF”). These factors are considered the most important factors in pathological and non-pathological angiogenesis [Advances in Cancer Research, 67: 281 (1995)]. VPF/VEGF is a protein having a molecular weight of about 40,000 constituted by homodimers, which had been reported to be independent molecules as vascular permeability factor (VPF) in 1983 [Science, 219: 983 (1983)] and as vascular endothelial growth factor (VEGF) in 1989 [Biochem. Biophys. Res. Comm., 161: 851 (1989)], but it has been revealed as the results of cDNA cloning that they are the same substance [Science, 246: 1306 (1989); Science, 246: 1309 (1989)] (hereinafter, the term “VPF/VEGF” is recited as “VEGF”). Beyond the activity of VEGF upon vascular endothelial cells described above, VEGF has also been shown to have a growth enhancing activity [Biochem. Biophys. Res. Comm., 161: 851 (1989)], a migration enhancing activity [J. Immunology, 152: 4149 (1994)], a metalloprotease secretion enhancing activity [J. Cell Physiol., 153: 557 (1992)], a urokinase and tPA secretion enhancing activity [Biochem. Biophys. Res. Comm., 181: 902 (1991)], and the like. Furthermore, VEGF has been shown to have an angiogenesis enhancing activity [Circulation, 92 suppl II: 365 (1995)], a vascular permeability enhancing activity [Science, 219: 983 (1983)], and the like as its in vivo activities. It has been reported that VEGF is a growth factor having extremely high specificity for vascular endothelial cells [Biochem. Biophys. Res. Comm., 161: 851 (1989)] and that four proteins having different molecular weight are present due to alternative splicing of mRNA [J. Biol. Chem., 267: 26031 (1991)].
Among diseases accompanied by angiogenesis, it has been reported that VEGF plays an important role in the proliferation or metastasis of solid tumors and formation of morbid states of diabetic retinopathy and rheumatoid arthritis. With regard to solid tumors, production of VEGF in a number of human tumor tissues has been reported, such as in renal carcinoma [Cancer Research, 54: 4233 (1994)], breast cancer [Human Pathology, 26: 86 (1995)], brain tumor [J. Clinical Investigation, 91: 153 (1993)], gastrointestinal cancer [Cancer Research, 53: 4727 (1993)], ovarian cancer [Cancer Research, 54: 276 (1994)], and the like. Also, results of a study on the correlation between VEGF expression quantity in tumors and survival ratio of patients in patients with breast cancer have revealed that tumor angiogenesis is more active in tumors expressing high levels of VEGF than low VEGF expression tumors and that the survival ratio is lower in breast cancer patients having high VEGF expression tumors than breast cancer patients having low VEGF expression tumors [Japanese J. Cancer Research, 85: 1045 (1994)]. It has been reported also that an anti-VEGF monoclonal antibody inhibited tumor growth in a xenograft model test system in which a human tumor was transferred into nude mice by subcutaneous transplantation [Nature, 362: 841 (1993)]. Also, it has been reported that, in a metastatic cancer model of a human tumor in nude mice, an anti-VEGF monoclonal antibody inhibited metastasis of the tumor [Cancer Research, 56: 921 (1996)]. Additionally, since a high concentration of VEGF was detected in human carcinomatous pleural perfusions and ascites, the possibility that VEGF is a major factor involved in the retention of pleural perfusions and ascites has been suggested [Biochimica et Biophysica Acta, 1221: 211 (1994)].
In diabetic retinopathy, abnormal angiogenesis causes retinal detachment and hemorrhage of the vitreous body, resulting in blindness, and it has been reported that angiogenesis in diabetic retinopathy and the expression level of VEGF in the patient's eye balls are positively correlative [New England J. Medicine, 331: 1480 (1994)]. Also, it has been reported that angiogenesis in a monkey retinopathy model is inhibited when the VEGF activity is inhibited by the intraocular administration of an anti-VEGF neutralizing monoclonal antibody [Arch. Ophthalmol., 114: 66 (1996)].
Progress in the morbid states of rheumatoid arthritis (destruction of bone and cartilage) is accompanied by angiogenesis, and it has been reported that a high concentration of VEGF is contained in the synovial fluid of patients with rheumatoid arthritis and that macrophages in joints of patients with rheumatoid produce VEGF rheumatoid arthritis [Journal of Immunology, 152: 4149 (1994); J. Experimental Medicine, 180: 341 (1994)].
VEGF receptors have been reported. These include fms-like tyrosine kinase (referred to as “Flt-1” hereinafter) [Oncogene, 5: 519 (1990); Science, 255: 989 (1992)] and kinase insert domain-containing receptor (referred to as “KDR” hereinafter) [WO 92/14748; Proc. Natl. Acad. Sci. USA, 88: 9026 (1991)]; Biochem. Biophys. Res. Comm., 187: 1579 (1992); WO 94/11499), which belong to the receptor type tyrosine kinase family. Each of Flt-1 and KDR is a membrane protein of 180 to 200 kilodalton in molecular weight which has an extracellular domain consisting of 7 immunoglobulin-like regions and an intracellular domain consisting of a tyrosine kinase region. It has been reported that VEGF specifically binds to Flt-1 and KDR at Kd values of 20 pM and 75 pM and that Flt-1 and KDR are expressed in vascular endothelial cells in a specific manner [Proc. Natl. Acad. Sci. USA, 90: 7533 (1993); Proc. Natl. Acad. Sci. USA, 90: 8915 (1993)]. With regard to Flt-1 in various diseases, it has been reported that, in comparison with vascular endothelial cells in normal tissues, expression of Flt-1 mRNA increases in tumor vascular endothelial cells of human glioblastoma tissues [Nature, 359: 845 (1992)] and tumor vascular endothelial cells of human digestive organ cancer tissues [Cancer Research, 53: 4727 (1993)]. Additionally, it has been reported that expression of Flt-1 mRNA is observed by in situ hybridization in vascular endothelial cells of joints of patients with rheumatoid arthritis [J. Experimental Medicine, 180: 341 (1994)]. These results strongly suggest that a VEGF/VEGF receptor Flt-1 system plays an important role in tumor angiogenesis. Although it has been reported that VEGF binds to Flt-1 and the intracellular domain is auto-phosphorylated [Science, 255: 989 (1992)], the detailed function of the receptor mechanism is still unclear. However, it has been discovered that knock out mice in which the Flt-1 gene was destroyed die after a fetal age of 8.5 to 9.5 days due to abnormal blood vessel construction caused by abnormal morphology of vascular endothelial cells during blood island formation in the early stage of development and subsequent angiogenesis. This had led to an assumption that Flt-1 has a function essential for the tube formation of vascular endothelial cells in angiogenesis [Nature, 376: 66 (1995)].
In view of the above, it is expected that an antibody which can inhibit biological activities of VEGF through its binding to VEGF receptor Flt-1 will be useful for the diagnosis or treatment of diseases in which their morbid states progress by abnormal angiogenesis, such as proliferation or metastasis of solid tumors, arthritis in rheumatoid arthritis, diabetic retinopathy, retinopathy of prematurity and psoriasis. However, an anti-VEGF receptor Flt-1 monoclonal antibody which can detect cells in which VEGF receptor Flt-1 is expressed and anti-VEGF receptor Flt-1 monoclonal antibody which can inhibit biological activities of VEGF has not been described in the art.
Generally, when a monoclonal antibody derived from non-human animal is administered to human, the monoclonal antibody is recognized as a foreign material so that an antibody against the monoclonal antibody derived from non-human animal is produced in the body. As a result, the antibody is allowed to react with the monoclonal antibody derived from non-human animal, and it is known that side effects are caused [J. Clin. Oncol., 2: 881 (1984); Blood, 65: 1349 (1985); J. Natl. Cancer Inst., 80: 932 (1988); Proc. Natl. Acad. Sci. USA, 82: 1242 (1985)], the monoclonal antibody is shortly cleared [J. Nucl. Med., 26: 1011 (1985); Blood, 65: 1349 (1985); J. Natl. Cancer Inst., 80: 937 (1988)], and that the treating effect of the antibody is decreased [J. Immunol., 135: 1530 (1985); Cancer Res., 46: 6489 (1986)].
In order to solve the above problems, it has been attempted that a monoclonal antibody derived from non-human animal is modified to a humanized antibody, such as a human chimeric antibody or a human CDR-grafted antibody (reconstructed human antibody), using gene engineering technique. The human chimeric antibody is an antibody in which an antibody variable region (V region) is derived from a non-human animal antibody and an antibody constant region (C region) is derived from a human antibody [Proc. Natl. Acad. Sci. USA, 81: 6851 (1984)]. It is reported that when the human chimeric antibody is administered to human, antibodies against the monoclonal antibody derived from non-human animal are not almost induced and the half-life in blood is prolonged six times [Proc. Natl. Acad. Sci. USA, 86: 4220 (1989)·. The human CDR-grafted antibody is an antibody in which the complementarity-determining region (CDR) of a human antibody is replaced with the CDR of an antibody derived from non-human animal [Nature, 321: 522 (1986)]. It is reported that in the experiment using a monkey, immunogenicity is lowered by the human CDR-grafted antibody as compared with a mouse antibody, and the half-life in blood is prolonged four to five times [J. Immunol., 147: 1352 (1991)].
Accordingly, when the chimeric antibody and the humanized antibody which specifically react with human VEGF receptor Flt-1, side effects are decreased and the half-life in blood is prolonged because no antibody against a monoclonal antibody derived from non-human animal is produced. Therefore, it is expected that these antibodies can treat diseases in which their morbid states progress by abnormal angiogenesis, such as proliferation or metastasis of solid tumors, arthritis in rheumatoid arthritis, diabetic retinopathy, retinopathy of prematurity and psoriasis, and the like.
In addition, with the recent progress of protein engineering and gene engineering, the production of smaller antibody molecules, such as a single chain antibody [Science, 242: 423 (1988)] and a disulfide stabilized antibody [Molecular Immunology, 32: 249 (1995)], have been tried. Since the single chain antibody and the disulfide stabilized antibody have a molecular weight lower than a monoclonal antibody or a humanized antibody, they are excellent in tissue transition property and clearance from blood and are applied to imaging and the like, a composite thereof with a toxin was prepared, and therefore, the treatment effect can be expected [Cancer Research, 55: 318 (1995)]. Therefore, it is expected that these antibodies can treat diseases in which their morbid states progress by abnormal angiogenesis, such as proliferation or metastasis of solid tumors, arthritis in rheumatoid arthritis, diabetic retinopathy, retinopathy of prematurity and psoriasis, and the like.